There are at least two commercially recognized botanical varieties of coffee, Coffea arabica and Coffea canephora. The Arabica coffees are basically of two types, the so-called Brazils and Centrals which are intermediate grade and so-called Milds which come principally from Colombia. The important canephora coffees are the Robustas which come primarily from Africa, Indonesia and Ecuador.
Of the two botanical varieties, the Arabica coffees are generally preferred because of their full-bodied aromatic flavor. Robustas are characterized by off-flavors such as earthy, bitter, tarry, or rubber-like flavors. For that reason, the Robusta coffees are typically much less expensive than the more flavorful Arabica coffees. It is therefore desirable to in some way lessen the Robusta off-flavor notes, that is remove the earthy, bitter, tarry or rubber-like notes so that more Robusta coffees can be used either alone or in a blend of Robusta and Arabica coffees without introducing the undesirable flavor notes.
Methods for upgrading the flavor of roasted Robusta coffees are known. For example, U.S. Pat. Nos. 4,226,891 and 4,234,613 both to Lewis teach methods for upgrading the flavor of roasted Robusta coffee. The former patent describes the use of an aqueous acetone solution to upgrade Robusta favor. The latter patent discloses the use of an aqueous alcohol solution to achieve the same results. Although the methods of both patents purportedly upgrade roasted Robusta coffee, care must be taken to prevent damaging those desirable flavor notes present in roasted Robusta coffee while removing the undesirable flavor notes.
It is an object of the present invention to provide a method of lessening the off-flavor notes of low-grade green coffee when said coffee is roasted.
A further object of the present invention is to provide a method of improving the flavor of low-grade coffee which method is safe for use in food processing and is relatively inexpensive.